中空纤维更新液膜传质性能的研究

研究了中空纤维更新液膜(HFRLM)技术的传质性能.以CuCl2水溶液-10%P204 煤油-盐酸为实验体系,研究结果表明,中空纤维更新液膜技术可以实现同级萃取-反萃,且总传质系数随料液相流速的增大而增大,在实验条件下,总传质系数受反萃相流速的影响较小.实验研究探讨了混合方式(料液与萃取剂混合和反萃剂与萃取剂混合)和体系分配系数对传质性能的影响.实验结果表明,由于相间分配系数的不同,总传质系数受混合方式的影响较大,以分配系数较大的一相与萃取相混合流经管程的方式对传质过程有利.     

液膜技术原理及中空纤维更新液膜

液膜技术可以实现萃取和反萃的耦合,具有独特的分离优势。因为具有非平衡传质的特性,液膜技术传质推动力大,萃取相用量很少。回顾了液膜技术的原理,指出液膜技术的关键在于形成一层厚度薄且相当稳定的液膜相。分析介绍了近年来发展起来的各种液膜技术的优缺点,提出了一种中空纤维更新液膜技术,其体积传质系数比传统萃取塔的大530倍。     

中空纤维支撑液膜技术处理含铜废水

重金属废水的处理在环境保护和重金属资源综合利用方面都受到广泛的关注.采用中空纤维支撑液膜技术,用CuSO4水溶液模拟工业含Cu(Ⅱ)废水,二(2-乙基己基)磷酸(D2EHPA)/煤油为液膜相,盐酸为接受相,研究了液膜相组成、两相流速、流动方式等因素对中空纤维支撑液膜过程传质性能的影响.结果表明,料液相在管程流动时的传质通量大于料液相在壳程流动时的传质通量,传质通量随着管、壳程两相流速的增大及液膜相中载体浓度的增加而增大.模拟实验结果表明,中空纤维支撑液膜技术可同时实现废水中Cu(Ⅱ)的去除与浓缩,处理效果好.废水中Cu(Ⅱ)的去除率达97%以上,富集液中Cu(Ⅱ)浓缩倍数达5倍以上.     

轴向扩散对中空纤维膜萃取器传质性能的影响

通过测量聚丙烯中空纤维膜萃取器壳程和管程流动的RTD曲线 ,证实了中空纤维膜器管程与壳程流动均较为复杂 ,与理想平推流和理想全混釜相差较大。膜器管程流动的轴向返混程度随着流速增加而减小 ,而膜器壳程流动的轴向返混程度随着流速的增加而增大。将两相流轴向扩散模型用于描述传质情况 ,比较了表观传质系数和真实传质系数 ,计算了中空纤维膜萃取器中真实的浓度剖面。结果表明 ,中空纤维膜萃取器轴向扩散导致表观传质系数比真实传质系数下降 30 %左右 ,所以在进行膜器设计和放大时 ,中空纤维膜器的轴向扩散不可忽略。     

LIX984N为载体的中空纤维更新液膜中铜的传递过程

以LIX984N为载体,煤油为稀释剂,H2SO4为反萃剂,研究了中空纤维更新液膜过程中铜的传递行为。考察了两相压差、铜离子浓度、两相流速、操作方式以及膜丝有效长度等对传质过程的影响。结果表明:膜丝两侧的操作压差对传质过程几乎没有影响;随着料液相中溶质Cu(Ⅱ)浓度的增大传质通量增大,而反萃相中的Cu(Ⅱ)浓度对传质过程几乎没有影响;传质通量会随着壳程料液流速的增大而增大,但管程侧反萃相的流速对传质过程影响很小;逆流和并流两种操作方式对传质过程的影响可以忽略,而膜丝有效长度的增加会导致单位面积平均传质通量的下降。     

中空纤维更新液膜处理含镍电镀废水

利用自制疏水聚偏氟乙烯(PVDF)中空纤维膜组件对中空纤维更新液膜处理含镍电镀废水过程中的影响因素进行了研究,考察了液膜两侧液相浓度、流速、萃取剂P204所占油相比例等因素对镍去除率的影响.并把中空纤维更新液膜和中空纤维支撑液膜处理效果进行了对比.     

螺旋状中空纤维膜萃取传质特性

在对中空纤维膜萃取以及螺旋管技术进行充分调研的基础上 ,选择水 -苯酚 - 30 %TBP煤油为实验体系 ,溶质由水相萃取到有机相 ,在不同结构的单束螺旋状中空纤维膜器中研究了螺旋管纤维膜管内外流速以及螺旋管结构等因素对传质系数的影响 .实验结果表明 ,螺旋管中空纤维膜可以有效地提高中空纤维膜的传质特性 .随着管内流速的增加 ,传质系数将有很大提高 ,而管外流速对于传质系数的影响则较小 .至于螺旋结构的影响为 :随着螺旋内径的减小或者是螺旋螺距的减小 ,总传质系数相应地有很大提高 .最后得到了在本实验条件下计算总传质系数K的关联式     

中空纤维支撑液膜法提取林可霉素的研究

研究了反萃相预分散中空纤维支撑液膜技术提取林可霉素的传质过程,实现了林可霉素的萃取和反萃过程的耦合。研究了萃取剂(正辛醇)体积分数、林可霉素质量浓度、原料液pH对分配系数的影响,膜组件操作过程中管程流量、壳程流量对总传质系数的影响,并得到最佳操作条件,建立了数学模型。结果表明,正辛醇体积分数为80%、林可霉素质量浓度为5.5 g/L、原料液pH=11时分配系数最大。膜组件最佳操作条件,原料液∶萃取相=500∶500(mL/min)。利用传质模型求得原料侧水相传质阻力1/kW、跨膜传质阻力1/kM、反萃侧水相传质阻力1/kS在总传质阻力所占比例分别为21%、74%、6%,其中跨膜传质阻力是传质阻力主要部分。     

螺旋管式膜强化传质过程的研究与进展

膜传质过程越来越为众多研究者关注,本文全面综述了近年来螺旋管式膜强化传质过程的机理以及研究进展,并结合膜萃取传质过程的特性,提出螺旋管式中空纤维膜强化膜萃取传质过程的机理,给出了螺旋管式中空纤维膜强化膜萃取的实验结果。结果表明,螺旋管式中空纤维膜比直管式中空纤维膜的传质系数可以大２～４倍。     

膜接触器中乳化液膜脱除Ni2+的研究

研究了以D2EHPA/煤油/HC1形成的微乳液体系在中空纤维膜接触器中萃取NiCl2水溶液中Ni2的过程,考察了D2EHPA和Ni2+浓度、水溶液酸度、两相流速对溶液中Ni2+的萃取率和传质性能的影响.结果表明,用D2EHPA/煤油/HCl形成的微乳液体系能有效萃取NiCl2水溶液中的微量Ni2+,增大微乳液中载体D2EHPA浓度和料液pH都能提高Ni2的萃取率和过程的总质系数,增加料液流速能显著提高Ni2+的萃取率和过程的总质系数,表明过程的传质阻力主要在水溶液相.     

Intensification of zirconium and hafnium separation through the hollow fiber renewal liquid membrane technique using synergistic mixture of TBP and Cyanex-272 as extractant

The novel synergistic mixture of TBP and Cyanex-272 is used as the extractant in the hollow fiber renewal liquid membrane(HFRLM) technique for Zr/Hf separation.The effects of the chemical and operational parameters such as HNO_3 concentration in the donor phase,NH4 F concentration in the acceptor phase,Cyanex-272 and TBP concentration in the liquid membrane phase,the lumen and shell side flow rates,and aqueous/organic volume ratio on the mass transfer and separation performance of HFRLM method were investigated.The obtained results reveal the intensification potential of proposed HFRLM technique for selective extraction of Zr over Hf with separation factor higher than 100.The HFRLM method provides two times higher mass transfer flux in comparison with hollow fiber supported liquid membrane(HFSLM).Also,the HFRLM method shows satisfactory stability for 700 min of continuous operation.The Zr ion transport through the LM phase follows the coupled co-transport mechanism and the diffusion in the renewal layer is recognized as the rate-controlling step in the HFRLM process.Moreover,the Zr mass transfer coefficient and molar flux in the HFRLM method are calculated in the range of 1×10~(-8)to 8.4×10~(-7) m·s~(-1) and 4.9×10~(-6) to 20.1×10~(-6) mol·m~(-2)·s~(-1),respectively.     

New liquid membrane technology for simultaneous extraction and stripping of copper(II) from wastewater

In this paper, a new liquid membrane technique, hollow fiber renewal liquid membrane (HFRLM), is presented, which is based on the surface renewal theory, and integrates the advantages of fiber membrane extraction, liquid film permeation and other liquid membrane processes. The results from the system of CuSO₄+D2EHPA in kerosene+HCl show that the HFRLM process is very stable. The liquid membrane is renewed constantly during the process, the direct contact of organic droplets and aqueous phase provides large mass transfer area. These effects can significantly reduce the mass transfer resistance in the lumen side. Then the mixture of feed phase and organic phase flowing through the lumen side gives a higher mass transfer rate than that of stripping phase and organic phase, because the aqueous layer diffusion of feed phase is the rate-controlling step. The overall mass transfer coefficient increases with increasing flow rates and D2EHPA concentration in the organic phase, and with decreasing initial copper concentration in the feed phase. The overall mass transfer coefficient also increases with increasing pH in the feed phase, and reaches a maximum value at pH of 4.44, then decreases. Also, there is a favorable w/o volume ratio of 20:1 to 30:1 for this process. Compared with hollow fiber supported liquid membrane and hollow fiber membrane extraction processes, HFRLM process has a high mass transfer rate. Mathematical model for the HFRLM process based on the surface renewal theory is developed. The calculated results are in good agreement with experimental results under the conditions studied.     

采用不同载体的中空纤维更新液膜Cu(Ⅱ)传质的研究(英文)

The extraction ability of organophosphorus extractant D2EHPA (di-2-ethylhexyl phosphoric acid) and hydroximic extractant Lix984N are investigated by the extraction equilibrium experiments. Effects of carrier concentration and organic/aqueous volume ratio on the mass transfer of hollow fiber renewal liquid membrane (HFRLM) are studied. Results show that, in the extracting process, kerosene and n-heptane are more suitable than methyl-isobutyl ketone, butylacetate and benzene as the diluents of D2EHPA or Lix984N. The favorable feed pH is 4.4 for D2EHPA and 2.6 for Lix984N. The mass transfer flux of HFRLM increases with carrier concentration and finally reaches a plateau. The mass transfer flux and the overall transfer coefficient increase with the or-ganic/aqueous volume ratio, reach the maximum and then decrease.     

Mass transfer modeling of membrane carrier system for extraction of Ce(IV) from sulfate media using hollow fiber supported liquid membrane

A theoretical and experimental study on the extraction and stripping of Ce(IV) ions from sulfate media using microporous hydrophobic hollow fiber supported liquid membrane has been performed. The experiments were made in the recycling mode. Tri-n-octylamine (TOA) was used as extractant diluted in kerosene and sodium hydroxide was use as strip solution. The mathematical model focused on the extraction side of a liquid membrane system. The aqueous feed mass transfer coefficient (k_i) and the organic mass transfer coefficient (k_m) which were calculated from the model were 9.47 X 10^-2 and 6.303 cm/s, respectively. Therefore, the rate controlling step is the diffusion of the cerium complex across a liquid membrane. In addition, the mass transfer modeling was performed and the validity of the developed model was evaluated with experimental data and found to tie in well with the theoretical value when the concentration of TOA was higher than 5% (v/v).     

Removal of Aniline from Wastewater Using Hollow Fiber Renewal Liquid Membrane

Hollow fiber renewal liquid membrane (HFRLM) method was proposed based on the surface renewal theory for removal of aniline from waste water. The system of aniline + D2EHPA in kerosene + HCl was used. Aqueous layer diffusion in the feed phase is the rate-control step, and the influence of lumen side flow rate on the mass transfer is more significant than that on the shell side. The resistance of overall mass transfer is greatly reduced because of the mass transfer intensification in the renewal of liquid membrane on the lumen side. The driving force of mass transfer can be considered as a function of distribution equilibrium, and the overall mass transfer coefficient increases with the increase of pH in the feed solution, HCl concentration and D2EHPA concentration, and decreases with the increase of initial aniline concentration. A mass transfer model is developed for HFRLM based on the surface renewal theory. The calculated results agree well with experimental results. The HFRLM process is a promising method for aniline wastewater treatment.     

The Transport of Copper(II) through Hollow Fiber Renewal Liquid Membrane and Hollow Fiber Supported Liquid Membrane

Abstract

In this paper, hollow fiber renewal liquid membrane (HFRLM) and hollow fiber supported liquid membrane (HFSLM) were used to simultaneously remove and recover copper(II) from aqueous solutions, and the transport performance of these two techniques were compared under the similar conditions for the system of CuSO₄ +D2EHPA in kerosene +HCl. The results showed that the HFRLM process was more stable than the HFSLM process. The HFRLM process had a higher overall mass transfer coefficient than that of HFSLM process in single-pass experiments. These were because the renewal effect of the liquid membrane layer could reduce the mass transfer resistance of the lumen side and replenish the loss of the membrane liquid in the HFRLM process. The transport results were better in the HFRLM process than that in the HFSLM process with recycling experiments. Therefore, HFRLM technique is a promising method for simultaneous removal and recovery of heavy metal from aqueous solutions.     

预分散溶剂萃取平衡与传质特性

预分散溶剂萃取(predispersed solvent extraction,简称PDSE）是一种新型的液-液萃取方法.该过程首先将溶剂制成胶质液体泡沫(colloidal liquid aphron ,简称CLA),同时借助胶质气体泡沫(colloidal gas aphron,简称CGA)实现溶质的分离.本文以磷酸三丁酯（TBP）-煤油为溶剂,以十二烷基苯磺酸钠（SDBS）为水相表面活性剂,以TWEEN 80为油相表面活性剂制备了胶质液体泡沫（CLA）. 用十六烷基三甲基溴化胺（HTAB）为水相表面活性剂制备了胶质气体泡沫（CGA）. 利用半间歇式PDSE过程萃取苯酚溶液.研究了pH值、表面活性剂浓度、相比等对萃取率和平衡分配系数的影响.实验发现,PDSE过程更适用于小相比（油相∶水相为1∶1000或更小）和极稀溶液的萃取.实验还发现, PDSE过程的萃取率随着CLA中TBP浓度的增加而增加, 随相比的增加而提高.利用刚性球模型计算了CLA的传质系数,并与传统的液滴进行了比较.在相同的粒径下,CLA比传统的液滴具有更高的分散相总传质系数;与传统萃取塔中存在的液滴相比,CLA也具有一定的优势.此外,对于两者K_da的比较,更体现了CLA的优越性.     

Transport of Au(CN)2 − by Mixtures of Amine Primene JMT and Phosphine Oxide Cyanex 923 Using the Pseudo-Emulsion Based Hollow-Fiber Strip Dispersion Technology

The transport of Au(CN)₂ ^? between alkaline aqueous solutions and organic phases consisting of a mixture of the amine Primene JMT and the phosphine oxide Cyanex 923 in xylene was studied using the pseudo-emulsion based hollow-fiber strip dispersion (PEHFSD) technology. The feed phase was passed through the lumen side, and the pseudo-emulsions of the extractant mixtures and NaOH were passed through the shell side in a countercurrent mode using a single hollow-fiber contactor for extraction and stripping. In this membrane technology, the strippant (NaOH solution) is dispersed in the organic (Primene JMT + Cyanex 923 in xylene) membrane solution in a tank with an impeller stirrer adequate to form strip dispersion. The pseudo-emulsion phase is circulated from the reservoir tank to the membrane contactor to provide a constant supply of the organic solution to the membrane fibers. Furthermore, this technology allows a direct contact between the organic and strip solutions, providing a greater area for stripping and facilitating the metal recovery from the strip solution once both phases are separated. Various hydrodynamic and chemical parameters, such as flow of feed phase, extractant mixtures and gold concentrations, organic diluents, variation in feed pH, and the selectivity of the system with respect to the transport of different metal-cyano complexes, were investigated. Aqueous and membrane mass transfer coefficients were estimated for the present system.